According to the teachings of modern nutritional science, the absence or insufficiency of trace elements such as iron, copper, manganese, zinc, selenium, fluorine and cobalt in the fodder of young animals leads to deficiency diseases which can be prophylactically prevented or even therapeutically eliminated by the administration of these trace elements. Thus it has been found in the practice of conventional methods of animal husbandry that suckling pigs, for example, do not attain the desired gains during the first phase of their rapid growth if their supply of iron is insufficient. In such cases anemia occurs, which is manifested by an excessively small amount of red blood corpuscles in the blood or of the red blood pigment, hemoglobin, contained in the red blood corpuscles. The yound animals are more sensitive to infectious diseases as a result of this imbalance in the blood.
Deficiency diseases which occur in practice, and the trace elements involved therein, are named in M. Kirchgessner's "Wirkstoffe in der praktischen Tierernahrung," Bayer. Landwirtschaftsverlag, Munich, 1966. In the case of swine anemia it is possible to remedy the iron deficiency responsible therefor by the parenteral injection of liquid iron preparations, such as aqueous iron-dextran complexes, for example.
The administration of iron salts can also achieve positive results. However, since the yound consume mainly mother's milk in the first days of life, it would be necessary to administer iron salt separately daily for an extended period of time--for the first 21 days of life in the case of piglets, for example. In large-scale hog raising operations, however, this is utterly impractical.